In the automotive and truck markets there is a continuing demand for smaller and lighter vehicles which in turn has resulted in a demand for smaller and lighter engines and drive train components (e.g., transmissions, axles, etc.). Because they are lighter and smaller these engines and drive train components must operate at higher speeds which, among other things, has led to a demand for lubricants having improved EP/anti-wear characteristics as well as high temperature stability characteristics.
EP/anti-wear agents heretofore employed in the art are exemplified by chlorinated aliphatic hydrocarbons such as chlorinated wax; organic sulfides and polysulfides such as benzyl disulfide, bis(chlorobenzyl)disulfide, dibutyl tetrasulfide, sulfurized methyl ester of oleic acid, sulfurized alkylphenol, sulfurized dipentene, and sulfurized terpene; phosphosulfurized hydrocarbons such as the reaction product of a phosphorus sulfide with turpentine or methyl oleate, phosphorus esters including principally dihydrocarbon and trihydrocarbon phosphites such as dibutyl phosphite, diheptyl phosphite, dicyclohexyl phosphite, pentylphenyl phosphite, dipentylphenyl phosphite, tridecyl phosphite, distearyl phosphite, dimethyl naphthyl phosphite, oleyl 4-pentylphenyl phosphite, polypropylene (molecular weight 500)-substituted phenyl phosphite, diisobutyl-substituted phenyl phosphite; metal thiocarbamates, such as zinc dioctyldithiocarbamate, and barium heptylphenyl dithiocarbamate; Group II metal phosphorodithioates such as zinc dicyclohexylphosphorodithioate, zinc dioctylphosphorodithioate, barium di(heptylphenyl)-phosphorodithioate, cadmium dinonylphosphorodithioate, and the zinc salt of a phosphorodithioic acid produced by the reaction of phosphorus pentasulfide with an equimolar mixture of isopropyl alcohol and n-hexyl alcohol.
The ash-producing detergents/dispersants heretofore used in the art include the oil-soluble neutral and overbased salts of alkali or alkaline earth metals with sulfonic acids, carboxylic acids, and certain organic phosphorus acids. The term "overbased" salt is used herein to designate metal salts wherein the metal is present in stoichiometrically larger amounts than the organic acid radical.
It is known to make overbased salts by contacting a reaction mixture comprising at least one organic material to be overbased, (e.g., sulfonic acid, carboxylic acid, phenol, certain classes of organic phosphorus acids), a reaction medium consisting essentially of at least one inert, organic solvent/diluent for said organic material to be overbased (e.g., mineral oil), a stoichiometric excess of at least one metal base, (e.g., sodium hydroxide, calcium hydroxide, magnesium oxide), at least one promoter, (e.g., methanol, phenol) with at least one acidic material, (e.g., CO.sub.2, SO.sub.2) at an elevated temperature (e.g., 60.degree.-300.degree. C.). Methods for preparing these overbased salts as well as an extremely diverse group of overbased salts are well known in the art and are disclosed, for example, in the following U.S. Pat. Nos. 2,616,904; 2,616,905; 2,616,906; 2,616,911; 2,616,924; 2,616,925; 2,617,049; 2,695,910; 2,723,234; 2,723,235; 2,723,236; 2,760,970; 2,767,164; 2,767,209; 2,777,874; 2,798,852; 2,839,470; 2,856,359; 2,859,360; 2,856,361; 2,861,951; 2,883,340; 2,915,517; 2,959,551; 2,968,642; 2,971,014; 2,989,463; 3,001,981; 3,027,325; 3,070,581; 3,108,960; 3,147,232; 3,133,019; 3,146,201; 3,152,991; 3,155,616; 3,170,880; 3,170,881; 3,172,855; 3,194,823; 3,223,630; 3,232,883; 3,242,079; 3,242,080; 3,250,710; 3,256,186; 3,274,135; and 3,492,231.
The book "Lubricant Additives" by M. W. Ranney, published by Noyes Data Corporation of Parkridge, N.J. (1973), discloses a number of overbased metal salts of various sulfonic and carboxylic acids and of phenols which are useful as detergent/dispersants in lubricating oil products. The book also entitled "Lubricant Additives" by C. V. Smallheer and R. K. Smith, published by the Lezius-Hiles Co. of Cleveland, Ohio (1967), similarly discloses a number of overbased sulfonates, phenates and carboxylates which are useful as dispersants. U.S. Pat. No. 4,100,082 discloses the use of neutral or overbased metal salts of organic sulfur acids, carboxylic acids and phenols as detergent/dispersants for use in fuels and lubricants. U.S. Pat. No. 4,627,928 discloses the use of overbased magnesium salts of substituted aromatic hydroxy carboxylic acids as dispersants, detergents or antioxidants for lubricants and fuels.
U.K. Patent 1,242,102 discloses a process comprising contacting at a temperature of at least 20.degree. C., (a) at least one compound selected from inorganic acids, the ammonium, amine and metal salts thereof, and inorganic acidic gases (e.g., SO.sub.2) which, in water, form acids stronger than carbonic acid, and (b) at least one overbased, carbonated Group I or Group II metal-containing complex in the presence of at least one peptizing agent comprising a material which is effective as a dispersing agent in a lubricating oil but which is not an overbased, carbonated, Group I or Group II metal-containing organic complex for a period of time for at least a portion of (a) to react with (b).
U.S. Pat. Nos. 4,507,215 and 4,579,666 disclose a composition comprising: (A) an acidic, neutral or overbased metal salt of (A)(I) at least one acid of the formula ##STR1## wherein each X and X.sup.1 is independently oxygen or sulfur, each n is zero or one, and each R.sup.1 is independently the same or different hydrocarbon based group, and (A)(II) at least one carboxylic acid of about 2 to about 40 carbon atoms, the ratio of equivalents of (A)(I) to equivalents of (A)(II) being in the range of about 0.5:1 to about 1:0; and (B) an olefinically unsaturated compound capable of reacting with active sulfur. Compositions comprising the foregoing composition reacted with active sulfur are also disclosed. Lubricants and functional fluids comprising the foregoing compositions are disclosed. A process comprising reacting active sulfur with an olefinically unsaturated compound in the presence of component (A) is also disclosed.
International Publication No. WO89/04358 discloses a composition comprising: (A) at least one neutral or overbased metal salt or boron-containing neutral or overbased metal salt of at least one acidic organic compound, the metal in said salt being selected from the group consisting of alkali metals, alkaline earth metals, zinc, copper, aluminum or a mixture of two or more of said metals; (B) at least one metal deactivator; and (C) at least one compound selected from the group consisting of (C-1) phosphorus-containing amide; (C-2) phosphorus-containing ester; (C-3) sulfur-coupled dithiocarbamate; (C-4) sulfur-coupled functionally-substituted organic compound represented by the formula ##STR2## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently H or hydrocarbyl groups; R.sup.1 and/or R.sup.3 may be G.sup.1 or G.sup.2 ; R.sup.1 and R.sup.2 and/or R.sup.3 and R.sup.4 together may be alkylene groups containing about 4 to about 7 carbon atoms; G.sup.1 and G.sup.2 are each independently C(X)R, COOR, C.dbd.N, R.sup.5 --C.dbd.NR.sup.6, CON(R).sub.2 or NO.sub.2, and G.sup.1 also may be CH.sub.2 OH, wherein X is O or S, each of R and R.sup.5 are independently H or a hydrocarbyl group, R.sup.6 is H or a hydrocarbyl group; when both G.sup.1 and G.sup.2 are R.sup.5 C.dbd.NR.sup.6, the two R.sup.6 groups together may be a hydrocarbylene group linking the two nitrogen atoms; when G.sup.1 is CH.sub.2 OH and G.sup.2 is COOR, a lactone may be formed by intramolecular condensation of G.sup.1 and G.sup.2 ; and x is an integer from 1 to about 8; and (C-5) mixture of two or more of any of (C-1) to (C-4). These compositions are useful as additives for lubricants and functional fluids, particularly hydraulic fluids, gear oils, greases and the like.
U.S. Pat. No. 4,755,311 discloses the preparation of monothiophosphoric acid using elemental sulfur or various sulfur sources capable of supplying sulfur to the reaction. The sulfur sources disclosed in this reference include sulfur halides, aromatic and alkyl sulfides, dialkenyl sulfides, sulfurized olefins, sulfurized oils, sulfurized fatty acid esters, sulfurized aliphatic esters of olefinic mono- or dicarboxylic acids, diestersulfides, sulfurized Diels-Alder adducts and sulfurized terpenes.